ipv6: sr: define core operations for seg6local lightweight tunnel

This patch implements a new type of lightweight tunnel named seg6local.
A seg6local lwt is defined by a type of action and a set of parameters.
The action represents the operation to perform on the packets matching the
lwt's route, and is not necessarily an encapsulation. The set of parameters
are arguments for the processing function.

Each action is defined in a struct seg6_action_desc within
seg6_action_table[]. This structure contains the action, mandatory
attributes, the processing function, and a static headroom size required by
the action. The mandatory attributes are encoded as a bitmask field. The
static headroom is set to a non-zero value when the processing function
always add a constant number of bytes to the skb (e.g. the header size for
encapsulations).

To facilitate rtnetlink-related operations such as parsing, fill_encap,
and cmp_encap, each type of action parameter is associated to three
function pointers, in seg6_action_params[].

All actions defined in seg6_local.h are detailed in [1].

[1] https://tools.ietf.org/html/draft-filsfils-spring-srv6-network-programming-01

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index 50181a9..0d72239 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -311,7 +311,8 @@ config IPV6_SEG6_LWTUNNEL
 	---help---
 	  Support for encapsulation of packets within an outer IPv6
 	  header and a Segment Routing Header using the lightweight
-	  tunnels mechanism.
+	  tunnels mechanism. Also enable support for advanced local
+	  processing of SRv6 packets based on their active segment.
 
 	  If unsure, say N.